Minister quits in protest over Brown's leadership

Gordon Brown suffered the most serious blow to his leadership today when a senior minister quit the Government.

Scottish Office Minister David Cairns walked out after refusing to make an oath of loyalty to the Prime Minister.

His is the most senior resignation since the latest bout of plotting against the Prime Minister erupted with the sacking of Siobhain McDonagh, a close friend of Mr Cairns.

It comes a day after the Standard reported that three ministers were considering their positions and quoted one minister as saying that concern about Mr Brown's leadership was widespread in the Government.

Mr Cairns, 43, was suspected by No 10 of criticising Mr Brown in private and Defence Secretary Des Browne was despatched to interrogate him about his views.

The former Catholic priest was described as emotional and torn by one source, who said his resignation was inevitable when he refused to deny that he believed Mr Brown was leading the party to electoral disaster.

A Downing Street statement said simply: "The Prime Minister has accepted David Cairns's resignation. The exercise of government demands collective responsibility."

The blow overshadowed another fight-back by Mr Brown's supporters. After a special political session of Cabinet, a string of heavyweight ministers and Labour grandees rallied behind the Premier. Deputy leader Harriet Harman said Britain needed a leader "with immense economic experience".

Earlier the National Executive Committee, Labour's ruling body, backed the Prime Minister by throwing out a rebel bid to start a process of seeking nominations for a leadership election.

Rebel ringleader Janet Anderson did not turn up and sent apologies by text message, though arguments were continuing over what the rules mean.

But these boosts were blighted by the drama in Scotland where Mr Cairns was effectively pushed into resigning. It started when his name was "outed" and friends suspected that No 10 was moving against him, to prevent him resigning at a more damaging time later.

The Inverclyde MP is the fourth departure after Ms McDonagh, Labour vice-chairman Joan Ryan and Barry Gardiner who quit an envoy role.

Two other ministers, whose names are known to the Standard, are said to be considering their position.

In other developments, a ministerial aide said privately that he may resign, saying Mr Brown was in his "death throes" and that more rebels were waiting "until the time is right".

It was also rumoured that a Cabinet minister is planning to quit if the party loses the Glenrothes byelection, expected to be on 6 November.

Earlier, Mr Brown told the political cabinet he was certain Labour can win the next election if it shows it has the best vision for Britain's future after the economic downturn is over.